1 files changed, 119 insertions, 0 deletions
diff --git a/configs/pulse.nix b/configs/pulse.nix
new file mode 100644
index 0000000..17c203c
--- /dev/null
+++ b/configs/pulse.nix
@@ -0,0 +1,119 @@
+{ config, lib, mylib, pkgs, ... }: let
+  pkg = pkgs.pulseaudio;
+  runDir = "/run/pulse";
+
+  pkgs_i686 = pkgs.pkgsi686Linux;
+
+  support32Bit =
+    pkgs.stdenv.isx86_64 &&
+    pkgs_i686.alsaLib != null &&
+    pkgs_i686.libpulseaudio != null;
+
+  alsaConf = pkgs.writeText "asound.conf" ''
+    ctl_type.pulse {
+      libs.native = ${pkgs.alsaPlugins}/lib/alsa-lib/libasound_module_ctl_pulse.so;
+      ${lib.optionalString support32Bit
+        "libs.32Bit = ${pkgs_i686.alsaPlugins}/lib/alsa-lib/libasound_module_ctl_pulse.so;"}
+    }
+    pcm_type.pulse {
+      libs.native = ${pkgs.alsaPlugins}/lib/alsa-lib/libasound_module_pcm_pulse.so;
+      ${lib.optionalString support32Bit
+        "libs.32Bit = ${pkgs_i686.alsaPlugins}/lib/alsa-lib/libasound_module_pcm_pulse.so;"}
+    }
+    ctl.!default {
+      type pulse
+    }
+    pcm.!default {
+      type pulse
+    }
+  '';
+
+  clientConf = pkgs.writeText "client.conf" ''
+    autospawn=no
+    default-server = unix:${runDir}/socket
+  '';
+
+  configFile = pkgs.writeText "default.pa" ''
+    .include ${pkg}/etc/pulse/default.pa
+    load-module ${toString [
+      "module-native-protocol-unix"
+      "auth-anonymous=1"
+      "socket=${runDir}/socket"
+    ]}
+    ${lib.optionalString (config.krebs.build.host.name == "au") ''
+      load-module ${toString [
+        "module-native-protocol-tcp"
+        "auth-ip-acl=127.0.0.1;10.23.1.0/24"
+      ]}
+    ''}
+    ${lib.optionalString (config.krebs.build.host.name != "au") ''
+      load-module ${toString [
+        "module-tunnel-sink-new"
+        "server=au.hkw"
+        "sink_name=au"
+        "channels=2"
+        "rate=44100"
+      ]}
+    ''}
+  '';
+in
+
+{
+  environment = {
+    etc = {
+      "asound.conf".source = alsaConf;
+      # XXX mkForce is not strong enough (and neither is mkOverride) to create
+      # /etc/pulse/client.conf, see pulseaudio-hack below for a solution.
+      #"pulse/client.conf" = mkForce { source = clientConf; };
+      #"pulse/client.conf".source = mkForce clientConf;
+      "pulse/default.pa".source = configFile;
+    };
+    systemPackages = [
+      pkg
+    ] ++ lib.optionals config.services.xserver.enable [
+      pkgs.pavucontrol
+    ];
+  };
+
+  hardware.pulseaudio = {
+    inherit support32Bit;
+  };
+
+  # Allow PulseAudio to get realtime priority using rtkit.
+  security.rtkit.enable = true;
+
+  system.activationScripts.pulseaudio-hack = ''
+    ln -fns ${clientConf} /etc/pulse/client.conf
+  '';
+
+  systemd.services.pulse = {
+    wantedBy = [ "sound.target" ];
+    before = [ "sound.target" ];
+    environment = {
+      PULSE_RUNTIME_PATH = "${runDir}/home";
+    };
+    serviceConfig = {
+      ExecStart = "${pkg}/bin/pulseaudio --exit-idle-time=-1";
+      ExecStartPre = pkgs.writeDash "pulse-start" ''
+        install -o pulse -g pulse -m 0750 -d ${runDir}
+        install -o pulse -g pulse -m 0700 -d ${runDir}/home
+      '';
+      PermissionsStartOnly = "true";
+      User = "pulse";
+    };
+  };
+
+  # TODO assert that pulse is the only user with "audio" in group/extraGroups
+  # otherwise the audio device can be hijacked while the pulse service restarts
+  # (e.g. when mpv is running) and then the service will fail.
+  users = {
+    groups.pulse.gid = config.users.users.pulse.uid;
+    users.pulse = {
+      uid = mylib.genid_uint31 "pulse";
+      group = "pulse";
+      extraGroups = [ "audio" ];
+      home = "${runDir}/home";
+      isSystemUser = true;
+    };
+  };
+}